HTDROC_-lRBOX XET.AL SULPHIDE COXPLESES

II’- C-KLOPEST_ADIESk-LCARBOXYLIROS TRITHIOC~RBOXATE COM-

PLESES

-1s a direct consequence of esperimental observations which will be described, in detail, elsewhere, we were led to esamine the preparation and properties of alkyl and aFI trithiocarbonate compleses of transition metals. In particular x-e were interested in those ccmpleses which could also have a carbonyl and/or hydrocarbon ligand. but had not been pm\-iowl- reported_ Several preparations of salts of the nronoalkyl esters of trithiocarbonic acid have been recorded throughout the early literature*, but esampie of the correspondin, m transition metal complese5 are scarce and poorly cha.racterised3. These ha\-e been variously stated to be less stable than the correq-tonding alkali metal derivatk-es. to decompose into the metal mercaptide and carbon dkulphide. and, for copper at lest, prepared from copper a&q-lmercaptide and carbon disulphidea. It is generally accepted, however. that metal derivatives of monoall+- esters of trithiocarbonic acid are fairly un~tablc (see q_ ref. s)_ Sever- thelws it seemed po&ble that this type of comples could be stabilised by the in- corporation of a good _z-bonding ligand into the molecule.

The trithiocarbonatz group has three +ulphur atoms, each in a formail>- different enx-ironment. and each potentialI- able to bond to a suitable metal, either independ-

ently or in conjunction with at lest one of the other two; in addition more than one metal atom could be invoI\-ed in comples formation ConsequentI_\- a wide variety of different compleses can be envkaged incorporating the different modes of bonding. ThG first paper dscribes the preparation and properties of two different types of trithiocarbonate complex and prosides additional information on the currently topical ,u-mercaptido compoun&c.

Iron forms the widest range of sulphur complesea. where the metal k in a low valenc\- state, and ako bonded to such ligands aa carbon monoside, nitric oside, phojphines, or a q-clopentadieq-I grciup. Several esampfes are dexribed in the preceding paper of two types of compounds (III) and 03, which could conceivably undergo carbon dklphide insertion to yield trithiocarbonates. Howe\-er, several trial esperimentsfailed to reveal the espected reaction. B:; contrast cyzlopentadien+3icar-

6s R. BRGCE, G. R. KSos

bon_vliron halide; reacted very readily at, or below, room temperature, with sodium all@ or c-1 trithiocarbonat~. The esperiment was best carried out in THF solution b_v reacting escess mercaptan with the calculated quantity of sodium h+-ide. at o3

or below, and then adding carbon dismlphide to produce a yellow solution of the salt of the desired acid. Dropwise addition of aTHF solution of cyclopentadienvldicarbon- yliron halide resulted in an immediate colour change and precipitation of sodiun halide. Chromato,qphy revealed a number of products; for the methyl and ethyl derivatives the major component of each mixture was [(II). R = CH,; C,H;: in appros. 73 ~b yield. Howe\-er. sodium phenyi trithiocarbonate appears to be unstable, even in the presence of a gross escczs of carbon disulphide. Consequentl?- the principal prodnct from such reactions wan the terminal mercaptider (III, R = C,H,) (gG--Sg “b) and onI>- q- O-’ 33 -0 of the trithiocarbonate comples (II, R = C,H,). Thee derivatives (II) are hig&ly cgkrltine. orange red solick, with melting points near to roe’, and are stabIe to air in the solid state. In solution decomposition occurs skm-I\- at ambient temperature, producing the same organometallic compound (1x2 found zka by-product during the preparation of (II).

When decomposition of the clicarbonyls (II) was deliberately induced by ir-

HYDROCARBOS 3fETAL SIJLPHIDE COMPLESES. II 69

radiating benzene solutions with UV light, one CO per molecule was eliminated very smoothly and mononuclear monocarbonyl compleses (IV) were obtained in high _\ield. This photolytic displacement of CO parallels the conversion of o-ally1 to z-ally1 complexes, described by Green and co-workerss. This similarity is further emphasized since the chelated trithiocarbonate group and the _z-ally1 group are isosteric, and thus the complexes (117 and the less stable _z-all\-l-x-c-clopentadienyliron carbon$ are analogous. The monocarbonyl derivatives (I?, R = CH,. C,H,, C&J are deep red air stable crystalline solids, having lower melting points (below 100') but greater solubilities than their precursors. They are sublimable at room temperature, but not without some decomposition involving Ioss of carbon disulphide.

The bridged mercaptide compleses (\2l are produced when the dicarbon-I

compounds are r&used in toluene. These are the thermodynamicali- favoured isomers when R = CH, and C,H,, but both known isomers when R = C6H5. This conversion may be followed SpectroscopicalIy; under the reaction conditions (III) are not stable but it is probable that the preferred sequence is

Unlike the stable isomers of (1‘). both (II) and (I\‘) can be chromatographed without difficulty, and do not appear to be unusually sensitive to acid.

ISFRIRED SPECTRI

The structures of compounds (II) and (I\‘) follon- from their analyses and infrared spectra.

The&carbon-ltrithiocarbonate complexes (II) show two fundamental stretching frequencic; in the terminal carbon_\-1 region (Table I) as espected, and both \-alues lie between those for (I) and (III)_ The monocarbon_\- complexes (113 each show a single terminal carbon\-1 frequency, and the position of this peak is almost insensitive

TABLE 1

ISFR.X-RED SPECTRh IS THE 3IE-K_IL. C.AR-ROS\-L REGIOS

VdueS (cIz?-~) obtained ;LS Ccl, solutions.

I =H, C,H, C,H, -

= .k CHCI, solution.

J_ Or_eaxornetaI. Chetn.. 6 (1966) 67-75

io R_BRUCE.G_ R_ K'C'OS

to the nature of the group R <cJ_ value for (IY) in Table I with values for c’) given in Table I in Ref_ I]_ This suggests that the S of the SR group is not bonded to an

iron atom, and taken w<th other evidence supports structure (It? but not structure (XI)- X comparison of the position of this carbon-l frequency [(IV); R = CH,), _‘@x$ cm-’ in Ccl,; 1956 cm-1 in CH,CI zj with that given for the recently reported ~IMIO~OUS dimeth)-klithiocarbamate cornpIes (IWO cm-1 in CH,CLJ reveals a shift in the expected direction; the larger eiectron reIeasing power of (CH,),S over CH,S promotes a higher ironxarbon bond order, reflected in a shift to lower frequency for the carbon)-1 group in the carbzmate complex.

‘51 0r!zc7 n-ems \ *

The zompounds discussed in this paper do not show the pronounced "~_Io"

bands common to ferrocene chemistFio; evt’n the C=S stretching frequency of (II)

espected to occur close to this re.gion1x-13, cxmot be asi.gned with certainty, although

it is obserx-ed that medium intensit)- banck in the region IO_~--IO~~ cm-l in (II) are

not present in (I\-). However. carbon-1 region apart, the most striking difference between rhe qectra of (11) and (I\‘) is the appearance of a strong band near 950-970

CEI-I in the Iarter series_ This band position appears to be sensitive to the nature of R, and is aIw-a_s accompanied by one. or two, other bands of !e_;ser inten&>-, now

known to be also charxteristic of R. Thus the ethyI derix-atives (I\], C,H,33,- MnfCO),~~ and (C,H,SC~:-,).Si,(%C,H3,?~ each ahow one other medium inter-sit>-

band nn the high frequcnc>- side, whilst the meth>--I derix-atiw (11-j shows two other

HYDROCARBOS METAL SULPHIDE COMPLEXES. II 71

medium to weak bands, one either side of the predominant band. This prircipai band is probably associated with a C-S stretching mode of the chelated

RS--C@ s:,

av .S/-

system. since both the location and intensity of the band can be reconciled with sach a grouping; to what extent this band can be attributed to a major contribution by

any of the canonical forms

g- _c . . i n-s&--

S-

R--;-C’-- R_&y-” . . ,--_ s . . ,--_ s . . ,‘:_

5 __ . . . .

cannot be judged_ One other easily rccognisable and characteristic (but unassigned)

difference between the spectra of the dicarbon-1 (II) and monocarbonyl (I\-) tri-

thiocarbonatcs occurs in the 5oo-600 cm-i region (Table 2). The dicarbonyls each exhibit three bands of medium to weak intensit-, the centre band being the strongest,

in the region gq-6~0 cm-i. This pattern changes for the chelated monocarbonyls (IV) which show only two bands (m -+- x-) in the 52o-560 cm-* region. Although out-

side the region usually assigned to a metal-sulphur stretching mode (loo-GO cm-i)*” it is noted that similar bands occur in the rclex-ant regions for (III), (73 and

tC,H,SCS,!,Si,(SC,H,),, but not for ~Si(SC,HJ,‘,,.

Sex-era1 features of the PAIR spectra of these sulphur complexes arc worth

noting. Referring to the \-alue 4 +-en in the table (TabIe 3) it is seen that the cyclo- pentadienyI resonance is \-irtun!!>- unchzmged b>- I-ariations of R within a group

[(II\. - $9 s; (z-j_ .- 5.4 -cl_ This su -nest; that an- inductive effect due to a change 33 - - in R, operating through the s\-stem, is minimal. _Xlso the shift in this cvclopentadienvl ring r I-alue from (II) to (I\‘) follows the same direction as found w&h (III) to (\I), when both s\-stem; increase the coordination of suiphur to metal. Such increased

r-\-aalucs ri-fernxf to TNS as internal standard in CS, solutions:.

Coi;rpo:utd CjHj CH, C,H, Cc*,

(Ii, It = CH,) J-91 (11. R = C,H,) 4.92 (II. R = C,H,) 4.96

i-40 6.so=

(I\-, Ii = CHd (I\?, K = C,H,) (IL-. R = C,HJ

i-15 S.63b.c

“_=g

n CH, quadruplet. b CH, triplet. ‘/ = 7.5 cps d Sharp; width at half-peak height 1.3 cps. C X-eE- sharp; widih at half-peak height < I cps.

J- O;~axomr!aI. Citt~t.. 6 (I96G) 67-75

7’2 R_BRUCE,G_ R. KSOS

shie!ding of ring protons 5~ expected when carhonyl groups attached to the metal

are replaced by other ligands of greater donor and:or poorer acceptor capacity.

Finahy, additional evidence against structure (L-1) ma!- be found from an inspection

of the T values for the group R of KS. These are usually rather strongl>- shielded when attached directly to an iron atom, and consequentI>- in (i’Ij would be expected to occur closer to those in (III) or (\-) than (II).

For generai esperimentai pmcedure and reagents xc Part I*_ The infrared spectra were obtained using a Perkin-Eimcr model 1-73 ,mting spectrophotometer,

and the PMR spectra recorded with a Perkin-Elmer 40 m.‘c instrument operating at

32.5 ‘_ Photochemical esperiments were conducted usin g the eq’lipment previously dwribxi_ l\Iicroanal~-se were b>- Dr. _A. BERSH_+RDI‘ (Max-Pianck Institutej and

osmometric molecuIar weight determinations by X-s. Sf. I<ILP~TRICK of this depart-

ment_

Cs~?o~~nf,?r;~~:s!cii~ar~oJ~sliro;: mzf&_st frifhiocarrrbo;fafc (II, fi! = CH,) JIethan&iof (2 mi. esces.;) KG added from a syringe to a suspenZon of sodium

hydride [I+ g, 50 "0 disnerGon in tinad oil. 0.04 mole) in THF (20 mIj at -;o’. I

u&r a CO, condenser. The mixture was stirrtul magneticall\- for 3 h when ga< cvoiution

had&& and the internal temperature had failen bcl& 0’. Carbon dijulphide (IO m? in THF (ro ml) xva~ added dropxke. cawin .g the x-him 5ul;pen&x-r to wmpktel~-

. , - cb~olvc., and ha\-mg a L-&XV solution. Cl-clopentndienvldicarbonvliron bromide

(6-9 g. o.oq mole\ in THk (50 ml) XL+ added to the co!d solution o\-er IO min. the mixture ~tl!cl~\-r;d ta warm to room temperature o\-er 14 h, evaporated, and extracted

with benzene (400 m!\. The estrncr wan chromnrographed on actix-e alumina using ~tiDl25 tIUZi3t.

C~d;_~~:.,,:fa~f-~-;~ .;~;i~~‘&‘-i;: yz _ “-I-O 1; Cf:: i-f :Yriir~~Jc‘ZY~,JI:czfir (II. R = C&j S dium hydride (I.& g, 30 *= diqkr5ion. o.oJ, _ g mole) in THF (20 mli uxs trt-a&d

at 0' with ethanethiol (?_I2 .g. 0.0% mole) in THF (-20 ml)_ Carbon disulphidc I” ml.

exe+;) in THF (20 mit was added after gas evolution had cesed (13 min!, and the

misture stirred at 0’ until a clear -ellow solution had been formed. CJ-clopentadien-l-

dicarbonyliron iodide (S-1 g. 0.0~7 mok) in THF (30 ml) was added dropwise, the

mixture stirred for 6 h at room temperature, esaporated. and the residue estracted

with benzene (zoo mi)_ The estract was filtered through kiesefguhr. and chromaio-

Lgraphed on neutral, _I h aimnina. Ether/petrol (I:I) eluted two bands; ether &ted a red ,-um (are mg) which rapidly decomposed, and a black solid (40 mg) de\-oid of

carbonyf absorption in the IR, and only slightly soluble in chloroform. Thee bands

IHDROCARBOS METAL SCLPHIDE COVPLEXES. 11 73

were not investigated further. The two bands eluted first were rechromatographed; petrol successively removed a trace of an organo-sulphur compound and (IV, R = C,ffJ (25 mg, I ?,A), identified by its IR spectrum_ A main orange-red band yielded the complex (II, R = C1H5) which was isolated. as orange red platelets (6.31 g, 74 %) from ether/petrol, m.p. C$Z_~‘_ (F ound: C. 37-95; H, 3.13; O,10.31; S, 30-33. C,H,FeO,S, calcd.: C, 3S.z; H. 321; 0, 10.1s; S, 30.59 “&_)

Thiophenol (4-4 g, 0.04 mole) in carbon disulphide (IO ml) ~-as added dropwise to a stirred suspension of sodium hydride (1.93 g, 50 “; disper&on, 0-0-f mole) in carbon dkulphide (30 ml) maintained at 05. -1 vex-y slight reaction occurred to give a pate yellow coIour_ After 15 min THF (aa ml) x-as added dropwise, causing immediate gas evofution and an esothermic reaction. The resulting Tellow solution was stirred for IO min and a solution of cyclopentadienyIdicarbonyIiron bromide (7.7 g, 0.03 mole) in carbon disulphide (100 ml! and THF (50 ml) w~as added slowly. The misture was stirred for r+ h, evaporated, extracted with benzene {l;so ml), fiitered through Kiesel- guhr and re-ex-aporated to small volume. Chromatography on actix-e alumina using petrwf &ted diphenyl. disufphide (370 mg), a red gum (250 mg) containing mostly diphenyl disulphide but &owing a single terminal metal carbonyl band in the IR, and a red sohd (130 mg) groA_t- contaminated with diphenyl dkulphide, but showing two bands in the terminal meta! carbon-1 region of the IR. Ether~petrol (I: I) &ted c?-cfof,~ntadii-n~fcficarbon~lirttrt ~~~~en~In~er~~~~tide (~_gr5 g, 56 :&)r (III, R = C&I,) and orange-red c-clopentadienyldicarbonyliron phenyl trithiocarbonnte (II, R = C,HJ (LOSS g, 35 “S], m. p. 106.5' from ether.‘petrol. (Found: C, 46.56; II, a&; 0, q-03; 5. - -4__$_ C,,H,,FeO& caled.: C, &._II; H, z-75; 0. S.Q; 5, ztj.53 “b-1

\t-hen the abo\-e reaction x-ti carried out uGn, fl onI\- a sfight e_sces:j of crri-1,011 di4phitk (3.2 g, o.o_+z rnoki, diphcnyl disulphide (SOO m& and (III. R = C,HJ (7-3

6. +i”,. _ i were the onlv product.; at room ttxnperaturc. \\hen this reaction was re- pcatcd and the misture r&ustxi, a yellow crystnhine product was obtained before the :rdditittn of the bromide at room tcmperarure; diphenyl diwlphidc (540 rns) and (III, IZ = C,H,I (z.;Sj .g. 6, ‘I;) were the only- products dctcct4 by- chromatography.

“Ti_:- lA,‘i’.f; ‘$*j‘:l’ljLl*C(~J ~+I~t)ilT.i7St*Oil Or* (21) iU (II -i

(:I‘: Zi = CH,. The dicarbon~-1 c0mpitx (3.0 g, o.(>i rt~ole) dis4x-ed in benzene (230 ml! xs;~rr irradiated for 6 h at room temperature. -4s in the ~uixquenr cspcrimen:s .Iilj) and b-.:1 \-i-r-y little decomposition occurred. The irradiated solution was evaporated and c!lrur;latct.~rapflcd~ on acti\-e alumina: petrol eluted an organo-sulphur compound (50 nrgj which \\-a$ (it-, n’== a-1,) (1.3s

rejected. ~_~~~fl~~?frifitiocarbo~r~rfo~c~c;;lujlcirfrrc~iiz~~~liroi~ c;lrbo;~yd

g, 7s “*I xx-as elutcd with 10 “& , ethrr/petrol. An anal>-tical sample, mp. fjs -, WI+ obtained s ruby-red prkms from ether,‘pt-trol; it wry volatile at room t~mpe,mturcz’ro-~ mm (Found: C, 35.16; H, 3.06; 0, 6.07; 5, j5.26; mol. wt., 277. C,HJ12cO& calcd.: C, 35-29; H, 2.9s; 0, $S7; S, 35_34yL,; moI_ w-t.. 272.) Pure ether e!utttd (11, R = CHJ (zoo mg) (7 00 recovec-).

(6j Iz z C,H;. The abow experiment was repeated using the ethyl deril-ative (11. R = C-H,) (3.0 g, 0.095 mole). Chromatography separated an organo-sulphur compound (band I) fsoo mg} (rejected) and (II, R = C,HJ (470 mg, 1-7 2; recovery) (band 3) from (~tl~itritlriocarbo)~cztc)c~cl~~e,ztcrdi~tz~lirow carbojl$ (IV, R = C,H,)

51 R. BRUCE, G. R. KSOS

(1X33 g,644;) (band 2) ruby-red cr\-sta.Is (ether), m-p. 60’. (Found: C, 37.6S; H. 3.71; 0. ~_/‘a; S. 33_37_ C,H,,FeOS, &cd.: C, 37-76; H, 3-53; 0,5_5g; S, 33-63 PA_)

(c) R = C,;i,. (P/~l~~trifhiocarbonafo)c~cZop#rtadiet~,~irolt carboql (IV, R = C,HJ (_rgo mg, 6z ?a) was obtained as deep red crystals, m-p. ga= (etheripetrol) from the diczrbonyl complex (II. R = C,H,j (S6o mg. 0.0023S mole) after 6 h irradiation_ (Found: C. 46.50; H, 3.30; 0. 5-q; S. zS.=$. C,,H,,FeOS, cakd.: C. 46.72; H. 3.02; 0, +-‘ig; S. zs.$.s 00.)

(a) R = CH,. _A soIution of cyclopentadienyldkarbonyliron methyl trithio- carbonate (2 g) in toIuene (30 mi) was refluxed for I h. causing the coiour of the solution to darken untiI it became brown-biack. The metal carbonyl retion of the infrared spectrum of this solution was recorded e\-elq- I 5 min ; initia.Iiy the intensity of the 2oq.q cm-1 and 2003 cm-l peaks decreased as a new peak idue to (11-j: at Ig6+ cm-1 develop&. but to\r-ards the end of the reaction this peak aIso decreased and \\‘a replaced by a sin,oIe peak at appros. 1030 cm-l (J’j- The toluene was evaporated at room temperature~Io-3 mm and the residual brown *“urn chromato,mphed in ether; petro! (I : I) on neutral. 4 h alumina. _‘i singIe olive-brown band was eluted (~-co 1950 cm-1 which yieIded (1’. R = CH,) (700 mg. 54:;). m-p. and mised m-p_ IOGIOS’, &er evaporation ad subimation (~oo’/ro-~ mm)_ The position of the meta carbonyl peak in the IR spectrum indicated that the product was the stable isomer’ of (J-, R =

CH,? - (6j R= C,H5. The decomposition of (II. R = C,H;I (I cj in toIuene {So mI)

at r&us was fofiowed spectroscopicaIl_ durin g I h. FolIowinS the work-up procedure described in (a), (l‘, R = C,HJ &go rng, 730&) was isolated and identified as the thermod~namicaily stable isomer b>- m-p. and IR (rco 1952 cm-x)_

(c) R = C,H,. C_vcIopentadienyIdicarbon_Iiron phenyl trithiocarbonate (11, R = CeH5j (150 rn& was converted after I h in boilin g toluene (30 ml) into both knots-n isomers of (\-, R = C,H,j*. Chromatography (neutrat, IO h alumina) using ether!petrol (I :+j separated the stable isomer (E_: mg. 13 a ,,) (rco appros. rgqo cm-l) from the Ies stabI+% isomer (<5 mg, 64 :.Gj (rco sgSo cm-l) and showed that (II) had been com- pteEei>- consumed.

_ICiiSO\VLEDGEXEST5

The auihors are gratefu1 to International Sickel Ltd., for generous supplies of iron carbon_vI. to the D.S.I.R.. for a research studentship (to R-B.), and to Dr_ PIER BLIDOS and his staff for the spectroscopic information.

Sodium a&-I or q-1 trithiocarbonates react with c_vcIopentadienyIdicarbon?_l- iron halide. producing c_vcIopentadienyIdicar’bon~liron alkvI or e-1 trithiocarbonates ;C5H5Fe(CO)&S3R~ which readily 10x carbon monoside. U1’ irradiation converts these dicarbonyls (R = CH,, C,H,, C,HJ into chelated monocarbonyls, (aIkyI- or arykrithiocarbonato)c~ciopentadienyIiron carbony &H,Fe(COjCS,Rl, which suffer carbon dk=ulphide eknmation in reflusin~ toluene yielding the known di-,u-mercaptido-

/_ Orgononrr?aI. Clicnr., 6 (x966) 67-75

XFDROC_RBOS METAL SULPHIDE COJIPLESES. II 75

Gs(cyclopentadienyIcarbonyIiron) [C5H5Fe(CO)SR& The IR and PXR spectra of

these complexes are discussed.

REFERESCES

XI. Aaun~. R. BRUCE ASD G. R. Kxos.~. O~~~t~omefaZ.Cl;ern.. 6 (1946) 1. C.M~ucs.Bcr.. 6 (rS73) 1316 B. HOLUBERG, J- Prak:. Ckcm., [?-I 73 (1906) “39. \V. E. DL-SCAS, E_ Or-r ASD E. E. REED, I&_ Ex,o. Chewr. (Im2. Dir*.). 23 (193x) 3Sr. 11. Ijijc~x_~ss. in E. ~\L~~R. _\Iefkodnz der Orga~zischor C&n& (Hotcbsz-Weyl). X’ol. IS. Sckz+-. Selm-. T~iZUR.erbi)tdil)!ge):. Thieme. Stuttgart. 1955. p_ SIP ct. sro. (a) R. B. Iixsc. I’. -\I. TREICHH~ _*XD F. G. X. STOSE. J- -4m. Ckem. Sot.. S3 (x96x) 3600. (t) P. >I. TREICHEL. J-H. MORRIS ASD F. G. X_ STOSE.].~ZUX. SW.. (x963) po_ B. F. H.irrxx ASD Pm L. PAUSOS. J. Ckem. Sm.. (1956) 3030. >\I. L. H. GREES -*SD A. S. STEAR. J. O~~um~nzrt~Z. Ckmr.. I (x96+) 230 and references cited therein. F. _A_ Co-rros _xsn J_ A. MCCLEVERTY, irror,p. C&w:.. 3 (1964) 139s~ 11. Ros~stlrc~r. Clxrnt. ItId. (Londm). (193s) 933. L. J- BELL~UY. in S. KBARXSCH. Orguxic Sufphtc~ COJJI~OUJZ& \-01. I. I’ergamon. Osford. 1961, p. 56. I<. ~_~KA~!OTO. Infrared Spectra of ZJ!orgai:ic and Coordirrafio?r Cornporo!ds, \Viley. Sew York. 1963. p_ =I;. XI. L. SH_~S~AR_~S_~R.~Y~~S~~ ASD C. C. P.ITEL, Sprcfrockim. =icta, 31 (x965) 95. R. BRUCE, 'C‘npubiished observations.

J_ Orgamn:etnZ. Chmr.. 6 (1~66) 67-75